What log formats are supported?

Any plain-text log that includes the words TRACE, DEBUG, INFO, WARN, WARNING, ERROR, or FATAL (case-insensitive) somewhere in the line. This covers most logging frameworks including Log4j, Logback, Winston, Python logging, and syslog.

Is my log data sent to a server?

No. All filtering happens entirely in your browser. Your log text never leaves your device.

What happens to lines that have no recognized level?

Unclassified lines are grouped under a separate "Other" category and shown or hidden with its own toggle. Multi-line stack traces typically fall here.

Can I filter a very large log file?

The tool works well for logs up to a few thousand lines pasted directly. For very large files (tens of thousands of lines) the browser may slow down — consider splitting the log first.

Does it handle WARN and WARNING both?

Yes. Both WARN and WARNING are recognized and grouped under the WARN level.

Log Level Filter

Name: Log Level Filter
Availability: InStock
Author: Nham Vu

Paste any log output, toggle levels to show or hide TRACE, DEBUG, INFO, WARN, ERROR, and FATAL lines with live color highlighting.

Paste Log Output

Filter by Level

Filtered Output

Paste log text on the left to begin.

Summary

Paste any log output, toggle levels to show or hide TRACE, DEBUG, INFO, WARN, ERROR, and FATAL lines with live color highlighting.

How it works

Paste or type your log text into the input panel on the left.
The tool auto-detects lines containing TRACE, DEBUG, INFO, WARN, ERROR, or FATAL.
Use the level toggle buttons to show or hide each level independently.
Filtered lines appear in the output panel with color-coded highlighting.
The stats bar shows the total count per level and how many lines are currently visible.
Click "Copy Visible" to copy only the filtered lines to your clipboard.

Use cases

Isolate ERROR and FATAL lines from a noisy application log.
Hide DEBUG and TRACE noise to review an INFO-level summary.
Count how many warnings appeared during a test run.
Share a filtered subset of logs with a colleague without the full noise.
Quickly scan server logs for unexpected FATAL entries.
Compare ERROR counts across different log sessions.
Strip DEBUG output from captured logs before filing a bug report.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu